In a project where I use bith the Treeview widget and a Gantt chart (Fusionchart widget) I have a Stack Overflow Error. Below you can find the stacktrace. Any help is more than welcome: An unhandled error occurred in the MxRuntime. java.lang.StackOverflowError at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632) at java.lang.ClassLoader.defineClass(ClassLoader.java:616) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) at java.net.URLClassLoader.defineClass(URLClassLoader.java:283) at java.net.URLClassLoader.access$000(URLClassLoader.java:58) at java.net.URLClassLoader$1.run(URLClassLoader.java:197) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:248) at mf.a(SourceFile:231) at mf.a(SourceFile:197) at mf.a(SourceFile:94) at me.executeAction(SourceFile:101) at com.mendix.systemwideinterfaces.core.UserAction.execute(SourceFile:57) at com.mendix.core.actionmanagement.CoreAction.call(SourceFile:457) at hC.b(SourceFile:182) at com.mendix.core.Core.executeSync(SourceFile:196) at hH.e(SourceFile:102) at hH.a(SourceFile:50) at hE.execute(SourceFile:99) at com.mendix.core.actionmanagement.CoreAction.call(SourceFile:457) at hC.b(SourceFile:186) at hC.a(SourceFile:150) at com.mendix.core.Core.commit(SourceFile:535) at com.mendix.core.Core.commit(SourceFile:513) at lC.a(SourceFile:71) at lz.a(SourceFile:34) at lz.a(SourceFile:54) at mf.a(SourceFile:78) at me.executeAction(SourceFile:101) at com.mendix.systemwideinterfaces.core.UserAction.execute(SourceFile:57) at com.mendix.core.actionmanagement.CoreAction.call(SourceFile:457) at hC.b(SourceFile:182) at com.mendix.core.Core.executeSync(SourceFile:196) at hH.e(SourceFile:102) at hH.a(SourceFile:50) at hE.execute(SourceFile:99) at com.mendix.core.actionmanagement.CoreAction.call(SourceFile:457) at hC.b(SourceFile:186) at hC.a(SourceFile:150) at com.mendix.core.Core.commit(SourceFile:535) at com.mendix.core.Core.commit(SourceFile:513) at lC.a(SourceFile:71) at lz.a(SourceFile:34) at lz.a(SourceFile:54) at mf.a(SourceFile:78) at me.executeAction(SourceFile:101) at com.mendix.systemwideinterfaces.core.UserAction.execute(SourceFile:57) at etc etc